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A Plea for the Improbable

AbstractSome authors have argued that the recent financial crisis, while antecedently improbable, was more probable than the leading models suggested. According to the Jet Propulsion Laboratory, the probability of launch failure of the Cassini spacecraft (mission to Saturn) was 1.1 x 10-3. According to the US Nuclear Regulatory Commission, the probability of a severe reactor accident in one year is between roughly 1 in a million and 1 in a 100,000. Augustin Cournot is famous for the principle that an event of small probability singled out in advance will not happen. The Energy Bulletin wrote: “Obama’s commitment to lift a moratorium on offshore drilling reflected the widely-held belief that offshore oil operations, once perceived as dirty and dangerous, were now so safe and technologically advanced that the risks of a major disaster were infinitesimal …” And yet a major disaster occurred.Much of my philosophical research has concerned the extremely improbable: events that we typically disregard because their probabilities are so low. And yet many such events should be important to philosophers, many of them should be important to scientists, and some of them should be important to all of us. I will survey more examples of improbable events in engineering, science, and daily life. I will discuss some of the mileage that philosophers have got out of such events in motivating philosophical positions. Then I will put them to philosophical work of my own. I will appeal to them to question some probabilistic orthodoxy, and to argue that most counterfactuals—statements about what would happen if things were different in particular ways—are false. (Here I especially invoke various extremely small probabilities that one finds in quantum mechanics and statistical mechanics.) Extremely improbable events also have ramifications for Pascal’s Wager, arguably the most famous argument for theism. I will conclude with a practical case that is important for our everyday life and for our future: responding to the prospect of global warming.